EFFECT OF LOW-MOLECULAR-WEIGHT HEPARAN-SULFATE ON ANGIOGENESIS IN THERAT CORNEA AFTER CHEMICAL CAUTERIZATION

Vascularization of the cornea occurs in many pathological conditions a nd can result in loss of visual acuity. It is also thought that vascul arization predisposes the cornea to reject grafts by facilitating the detection of foreign antigens in donor material. A rat corneal assay f or angiogenesis was adopted in the present study to evaluate the possi ble angiostatic activity of a low molecular weight heparan sulphate (L MW-HS). Corneal lesions were induced by chemical cauterization at 2 mm from the corneoscleral limbus. Rats were randomized to receive two dr ops/eye four times daily, for 6 days, of a solution of LMW-HS in vehic le (2.5% carboxymethylcellulose), heparin, heparin plus hydrocortisone , or vehicle alone. After a 6 day-treatment period, the eyes were perf used with india ink and the degree of neovascularization was evaluated . In rats treated with vehicle alone a dense vascular network extendin g from the corneoscleral limbus to the cauterized site was observed; o n the contrary, a markedly reduced vascular network was evidenced in a nimals treated with LMW-HS. The distribution of basic fibroblast growt h factor (bFGF) in the cauterized cornea was also evaluated by using a n immunohistochemical method. A marked bFGF immunoreactivity was demon strated in corneal epithelium and stroma of control rats 12-48 hours a fter the cautery. These results lead to the assumption that LMW-HS cou ld be used in ophthalmology to inhibit corneal neovascularization.